Piston expander



Jan. 22, 1935. 0.1;. ULVANG 1,988,707

PI STON EXPANDER Filed March 23, 1933 INVENTOR.

ATTORNEY.

Patented Jan. 22, I935 This invention relates to piston expanders, and has for its principal'object to provide a more eflicient and simple device of this character than heretofore known.

Another object is to provide a resilient expander having means associated therewith for selective adjustment of its resiliency.

Still other objects and advantages of the invention will appear in the following description thereof.

Referring now to the accompanying drawing, forming part of this application, and wherein like reference characters indicate like parts:

Figure 1 is a cross sectional view of the lower end or skirt of a common internal combustion engine piston having three of the expanders applied thereto.

Figure 2 is an elevation of one of the expanders illustrated in Figure 1.

Figure 3 is a perspective view of a modified form of resilient expander.

I am aware that resilient expanders for pistons having split skirts are old, but such expanders are not designed for the express purpose'of applying expansion to that portion of the piston requiring same, but rather to applying expansive stress more generally to the lower end of the piston, whereas it is well known to those in a cylinder is uponthe opposite sides thereof at right angles to the wrist pin connection therein, thus the necessity of expanding the skirt of the piston in a manner only to compensate for such wear.

For example the expander known as a bull ring is simply snapped into the skirt of the piston and applies its stress uniformly thereabouts, but only upon a limited annular area about the piston as compared with my preferred form of expander for such purpose. It is to be understood that the instant form of expander is applicable to either a split skirt piston or a solid one, and it may here be stated that to many at least it is quite surprising what effect in the way of diametrical expansion may be had in the skirt of the common piston by application of two of the most simple forms of the invention, as for example illustrated in Figure 3 of the drawing, andthese being snapped into place simply with the fingers of the hand.

Referring now particularly to Figure 1 of the drawing, the numeral 1 represents the skirt of a common piston to which is applied one type of the improved expander as at 2, and a different type of the expander as at 3, though, of course,

it is to be understood that different types of expanders in the same piston are not correct in practice, but are here shown simply to illustrate the two different kinds of expanders. The one illustrated at 2 is that type shown in Figure 2 5 of the drawing in which is installed an adjustable stiffem'ng element in the form of a turnbuckle 4. I

In providing the type of expander or spring illustrated at 2, it is preferred that the general shape be as illustrated, having an arcuately shaped or bowed central portion with the ends arched in reverse relation and. centrally of the middle portion is an oval or elliptically formed opening 5 in which is installed the turnbuckle 4, the oppositepintles 6 of which are provided with right and left hand threads so that the turning of the adjusting element of the turnbuckle will either extend or retract the pintles uniformly.

The advantage of such an adjustable spindle will be appreciated when it is considered that, extreme nicety of expansion from time to time is essential for proper relationship of the piston to the cylinder as wear takes place. Such ad justment may be accomplished from time to time without the renewal or careful selection of an expander for a specific requirement. versed in the art that the wear of the piston It is readily appreciated that if an expander having no adjustability is selected which is a trifle too stifi, it will cause decided and necessarily damaging wear until finally automatic adjustment takes place, and then will last only for a given time. However, where this more careful adjustment is not necessary or deemed advisable, the simpler form of expander as illustrated at 3, or the one shown in Figure 3 of the drawing at 7 may be employed, and in which instance the effect of the expander only utilized to the limit of its inherent properties. The illustrations at 3 and '7 in Figure 1 may represent an expander such as shown in Fig. 3 or one as shown at 2, without the'auxiliary stiffening device as previously described, or with it as preferred.

An advantage resides in such an expander as shown at 2 without the stiffener in that it is much wider than the expander shown at '7 and provided with spaced contact terminals 8 at either end thereof, though, of course, necessitating two holes or depressions within the inner wall of the skirt for registration therewith. This materially spreads the effect of the expander longitudinally of the skirt, substantially difiering from the effect of a bull ring expander as previously mentioned.

For an abnormally wide expander the central portion may be cutaway as indicated in dotted lines at 9 upon either one side or both as required, depending upon the position of the expander in the piston.

v Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

1. A skirt expander for pistons comprising a flat wide spring having an arcuately shapedceritral portion with a central opening thereosclua L. I'I'LVANG. 

